Git commits in Moodle 3.5.7 by Tim Hunt

commit e8b72dabe6cc434a96d78cca922f2d6e6884d4b6
Author: Tim Hunt <T.J.Hunt@open.ac.uk>
Date:   Fri, 17 May 2019 19:22:19 +0800
Tag:    v3.5.7

MDL-65636 filter_multilang: add some basic unit tests